Lead in petrol subsititues
Discussion
I like to use Millers VSP
http://www.frost.co.uk/item_Detail.asp?productID=8...
Like the Castrol stuff, it is approved by the FBHVC and also contains an octane booster like the Valve master Plus.
But I have heard, as AJAX50 says, that frequently changing is not recommended.
http://www.frost.co.uk/item_Detail.asp?productID=8...
Like the Castrol stuff, it is approved by the FBHVC and also contains an octane booster like the Valve master Plus.
But I have heard, as AJAX50 says, that frequently changing is not recommended.
What has been said is mostly true however you could use TetraBoost with no problems, this is because TetraBoost is what makes genuine 4 Star Leaded petrol, i.e. the same stuff as supplied by Bayford & Co. You would still have to order it through the mail though. 
Rich...
http://www.leadedpetrol.co.uk/
http://tetraboost.com/
Rich...http://www.leadedpetrol.co.uk/
http://tetraboost.com/
TetraBoostHi All , correct me if I`m wrong but unleaded burns much hotter than the old leaded fuel and is much more volatile, which is why valve seat inserts and Valve faces faces suffer pitting. The exhaust valve , seat and guide cannot dissipate the heat from the combustion quickly enough. Lower compression engines don`t seem to suffer from this syndrome at all for obvious reasons. War time and post war engines often ran `Pool petrol` which was extremely poor grade fuel. The best was kept for the avaition industry.In those far off days de carbonising and re cutting, grinding or replacing valves occured every 3/6000 miles or less anyway.These issues were caused by poor oil, Oil consumption and poor grade fuel .These days,the motoring public expect far more of there classic and forget what actually did happen 50 or more years ago in the trade. I`m sure that the current grades of fuel are more than capable of running any engine without the need for all these additives. Especially those with alloy heads and seat inserts, which need no additive at all.
I would be interested to know how any of these additives can actually lower the combustion temperature. With a high compression engine it only the problem of heat dissipation/detonation is worse. Squeeze a gas it gets hot, squeeze it more ,it gets much hotter. Anything over 9/1 On Jaguar engines will cause a det problem no matter what additive is used. This is the reason why we here developed a programmable igniton system, which overcomes the problem.
I would be interested to know how any of these additives can actually lower the combustion temperature. With a high compression engine it only the problem of heat dissipation/detonation is worse. Squeeze a gas it gets hot, squeeze it more ,it gets much hotter. Anything over 9/1 On Jaguar engines will cause a det problem no matter what additive is used. This is the reason why we here developed a programmable igniton system, which overcomes the problem.
Hi, I used to buy my castrol additive from the MG owners club in Cambridgeshire, quite good price as I remember. see http://www.mgocspares.co.uk/acatalog/MGOC_Spares_L...MGB59.html
I used to use millers but much more expensive, the bottle only treats 40 litres whereas the castrol is about 250 I think.
I used to use millers but much more expensive, the bottle only treats 40 litres whereas the castrol is about 250 I think.
Edited by AC Motors on Saturday 7th March 13:48
The volatility of petrol has not really changed over the years. There is a difference summer to winter. If you add Tetraeythyllead (TEL) at .15gms/litre to 95 RON unleaded you get about 97 RON depending on the blend. Petrol is blended at a refinery from 15 to 20 different components each with a range of characteristics that together meet the required standards, which are much more extensive than RON.
TEL is itself volatile, a heated inlet manifold can cause partial separation of the mixture that can be unevenly spread between cylinders, so some may be RON rich and others RON poor, similarly for lead but not necessarily in line with RON. I wonder if this is the cause of the Jaguar compression ratio problem? Do jaguars with unheated manifolds suffer the same effects you describe? I'd be intersted to know, I'm thinking of changing the twin SU's on mk Mk2 to fuel injection.
TEL is itself volatile, a heated inlet manifold can cause partial separation of the mixture that can be unevenly spread between cylinders, so some may be RON rich and others RON poor, similarly for lead but not necessarily in line with RON. I wonder if this is the cause of the Jaguar compression ratio problem? Do jaguars with unheated manifolds suffer the same effects you describe? I'd be intersted to know, I'm thinking of changing the twin SU's on mk Mk2 to fuel injection.
RW774 said:
Hi All , correct me if I`m wrong but unleaded burns much hotter than the old leaded fuel and is much more volatile, which is why valve seat inserts and Valve faces faces suffer pitting. The exhaust valve , seat and guide cannot dissipate the heat from the combustion quickly enough. Lower compression engines don`t seem to suffer from this syndrome at all for obvious reasons. War time and post war engines often ran `Pool petrol` which was extremely poor grade fuel. The best was kept for the avaition industry.In those far off days de carbonising and re cutting, grinding or replacing valves occured every 3/6000 miles or less anyway.These issues were caused by poor oil, Oil consumption and poor grade fuel .These days,the motoring public expect far more of there classic and forget what actually did happen 50 or more years ago in the trade. I`m sure that the current grades of fuel are more than capable of running any engine without the need for all these additives. Especially those with alloy heads and seat inserts, which need no additive at all.
I would be interested to know how any of these additives can actually lower the combustion temperature. With a high compression engine it only the problem of heat dissipation/detonation is worse. Squeeze a gas it gets hot, squeeze it more ,it gets much hotter. Anything over 9/1 On Jaguar engines will cause a det problem no matter what additive is used. This is the reason why we here developed a programmable igniton system, which overcomes the problem.
I would be interested to know how any of these additives can actually lower the combustion temperature. With a high compression engine it only the problem of heat dissipation/detonation is worse. Squeeze a gas it gets hot, squeeze it more ,it gets much hotter. Anything over 9/1 On Jaguar engines will cause a det problem no matter what additive is used. This is the reason why we here developed a programmable igniton system, which overcomes the problem.
AJAX50 said:
...a heated inlet manifold can cause partial separation of the mixture that can be unevenly spread between cylinders...
Chaps, not trying to take the thread off at a tangent but can either of you explain the original thikning behind heated inlet manifolds? I would have thought the idea was to keep the inlet gas a cool as possible to increase air mass and hence power, obviously not, but what are the pros and cons? Rich... RW774 said:
lots of interesting stuff about the properties fo fuel in classic cars
RW774 said:
Heated manifolds Prevent carb / manifold freezing. Still no explanation of the compression temperature greater with unleaded than leaded.
The problems with the Jag, are cylinder head design,flowrate/ swirl( there isn`t any)great in its day, not now.
That depends on which Jaguar head.The problems with the Jag, are cylinder head design,flowrate/ swirl( there isn`t any)great in its day, not now.
The 'B' Type head with the offset inlet ports is supposed to give good swirl and generates it's torque lower down the rev range than the later straight port head. Back in period some racers preferred the B head for saloon racing. Warren Pearce made a triple carb manifold to fit it. These days some of the XK Challenge series racers prefer the B type head too. Guy Broads now produce a triple carb manifold to work with it. The weight of the XKs makes this a good combination. Harry Weslake was a great believer in curved inlet ports to promote swirl.
RW, Adhex,why is swirl desirable?
RW774 said:
Heated manifolds Prevent carb / manifold freezing. Still no explanation of the compression temperature greater with unleaded than leaded.
The problems with the Jag, are cylinder head design,flowrate/ swirl( there isn`t any)great in its day, not now.
The problems with the Jag, are cylinder head design,flowrate/ swirl( there isn`t any)great in its day, not now.
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